Geologic Cross Section D–D’ through the Appalachian Basin from the Findlay Arch, Sandusky County, Ohio, to the Valley and Ridge Province, Hardy County, West Virginia By Robert T. Ryder, Robert D. Crangle, Jr., Michael H. Trippi, Christopher S. Swezey, Erika E. Lentz, Elisabeth L. Rowan, and Rebecca S. Hope Scientific Investigations Map 3067 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Suzette M. Kimball, Acting Director U.S. Geological Survey, Reston, Virginia: 2009 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: Ryder, R.T., Crangle, R.D., Jr., Trippi, M.H., Swezey, C.S., Lentz, E.E., Rowan, E.L., and Hope, R.S., 2009, Geologic cross section D–D’ through the Appalachian basin from the Findlay arch, Sandusky County, Ohio, to the Valley and Ridge province, Hardy County, West Virginia: U.S. Geological Survey Scientific Investigations Map 3067, 2 sheets, 52-p. pamphlet. ISBN 978–1–4113–2357–5 iii Contents Introduction.....................................................................................................................................................................................................................................1 Construction of the Cross Section ..............................................................................................................................................................................................1 Structural Framework ...................................................................................................................................................................................................................3 Basement Structures ...........................................................................................................................................................................................................4 Thin-Skinned Structures ......................................................................................................................................................................................................6 Stratigraphic Framework ..............................................................................................................................................................................................................7 Lower Cambrian to Upper Ordovician Siliciclastic and Carbonate Strata ..................................................................................................................7 Upper Ordovician to Lower Silurian Siliciclastic Strata ...............................................................................................................................................11 Lower Silurian to Middle Devonian Carbonate and Evaporite Strata ........................................................................................................................12 Middle Devonian to Lower Mississippian Siliciclastic Strata .....................................................................................................................................13 Middle and Upper Mississippian Carbonate Strata ......................................................................................................................................................16 Upper Mississippian, Pennsylvanian, and Permian Siliciclastic Strata ....................................................................................................................16 Acknowledgments .......................................................................................................................................................................................................................17 References Cited..........................................................................................................................................................................................................................17 Appendix A—Table summarizing drill holes, stratigraphic units, and depths of stratigraphic units in cross section D–D’ .....................................28 Appendix B—Scale, units, and depths for gamma-ray logging runs .................................................................................................................................52 Figures [On map sheets] 1. Map of Ohio, West Virginia, Pennsylvania, and adjoining States showing location of cross section D–D’ and selected tectonic features 2. Correlation of Paleozoic rocks along cross section D–D’ in Ohio and West Virginia 3. Figure showing the Broad Top and Plateau sheets of Wilson and Shumaker (1992) iv Tables 1. Drill holes used to construct cross section D–D’ ....................................................................................................................................................2 Conversion Factors Multiply By To obtain Length foot (ft) 0.3048 meter (m) meter (m) 3.281 foot (ft) mile (mi) 1.609 kilometer (km) kilometer (km) 0.6214 mile (mi) Geologic Cross Section D–D’ Through the Appalachian Basin from the Findlay Arch, Sandusky County, Ohio, to the Valley and Ridge Province, Hardy County, West Virginia By Robert T. Ryder, Robert D. Crangle, Jr., Michael H. Trippi, Christopher S. Swezey, Erika E. Lentz, Elisabeth L. Rowan, and Rebecca S. Hope Introduction 2001) but are of more limited extent geographically and of the region. Several abrupt bends in the section, how- stratigraphically. ever, are required to accommodate key drill holes that Although specific petroleum systems in the penetrate the entire section of Paleozoic sedimentary Geologic cross section D–D′ is the second in a Appalachian basin are not identified on the cross sec- rocks. In general, cross section D–D′ follows the line of series of cross sections constructed by the U.S. Geo- tion, many of their key elements (such as source rocks, section used by Ryder (1991) in his stratigraphic study logical Survey (USGS) to document and improve reservoir rocks, seals, and traps) can be inferred from of Cambrian and Ordovician rocks. understanding of the geologic framework and petro- lithologic units, unconformities, and geologic structures The locations of the tops of each stratigraphic unit leum systems of the Appalachian basin. Cross section shown on the cross section. Other aspects of petroleum penetrated in the 13 deep drill holes were converted D–D′ provides a regional view of the structural and systems (such as the timing of petroleum generation from depth in feet (ft) below kelly bushing (KB) to stratigraphic framework of the Appalachian basin from and preferred migration pathways) may be evaluated depth below ground level (GL), and then plotted on the Findlay arch in northwestern Ohio to the Valley by burial history, thermal history, and fluid flow models the cross section with respect to mean sea level (MSL). and Ridge province in eastern West Virginia, a distance based on information shown on the cross section. Cross Detailed depth information for the tops of the strati- of approximately 290 miles (mi) (fig. 1 on sheet 1). section D–D′ lacks the detail to illustrate key elements graphic units in each drill hole is reported in appendix The information shown on the cross section is based of coal systems (such as paleoclimate, coal quality, A. In addition to the 13 deep drill holes used to con- on geological and geophysical data from 13 deep drill and coal rank), but it does provide a general geologic holes, several of which penetrate the Paleozoic sedi- struct the cross section (table 1), some of the details of framework (stratigraphic units and general rock types) mentary rocks of the basin and bottom in Mesopro- Pennsylvanian stratigraphy were obtained from “shal- for the coal-bearing section. Also, cross section D–D′ terozoic (Grenville-age) crystalline basement rocks. low” USGS coreholes in northern West Virginia. Data may be used as a reconnaissance tool to identify This cross section is a companion to cross section E–E′ from USGS corehole 6 (Dulong and others, 2002) were plausible geologic structures and strata for the sub- (Ryder and others, 2008) that is located about 25 to 50 projected into the cross section at drill hole 9, whereas surface storage of liquid waste (for example, Colton, mi to the southwest (fig. 1). Cross sections D–D′ and data from USGS corehole 10 (Nick Fedorko, West 1961; Lloyd and Reid, 1990) or for the sequestration of E–E′ update earlier geologic cross sections through the Virginia Geological and Economic Survey (formerly), carbon dioxide (for example, Smith and others, 2002; central Appalachian basin by Renfro and Feray (1970), unpub. data, 2003) were projected into the cross section Lucier and others, 2006). Bennison (1978), and Bally and Snelson (1980) and a between drill holes 10 and 11. In addition, data were stratigraphic cross section by Colton (1970). Published obtained from shallow coreholes in eastern Ohio near cross sections through parts of the basin show more drill holes 6 to 8 (Couchot and others, 1980) and from Construction of the Cross Section structural detail (for example, Shumaker, 1985; Wilson, selected wells in northern West Virginia between drill 1985a,b,c; Kulander and Dean, 1986; Wilson and holes 10 and 11 (Boswell and others, 1987; Lewis, Shumaker, 1992) and stratigraphic detail (for example, Cross section D–D′ is oriented northwest- 1983; West Virginia Geological and Economic Survey, Ryder, 1991, 1992; de Witt and others, 1993; Hettinger, southeast, approximately normal to the structural grain 2005) and between drill holes 11 and 12 (Schwietering, 2 Geologic Cross Section D–D’ From the Findlay Arch, Ohio, to the Valley and Ridge Province, West Virginia Table 1. Drill holes used to construct cross section D–D’. Drill- American Latitude Longitude Lithologic Cored intervals (ft) Total Age of oldest rocks drilled hole Name used in text Location Petroleum (decimal (decimal log and formation depth (ft) (formation) no. Institute no. degrees) degrees) Ohio 1 East Ohio Gas Company Townsend Township, Sandusky Co., Ohio 34–143–20077 41.37085 -82.9066 Yes1 3,123 Mesoproterozoic (metamorphic and No. 1–2171 V. and I. Haff (Clyde 7.5-min quadrangle) igneous rocks). 2 Pure Oil Company Greenfield Township, Huron Co., Ohio 34–077–20025 41.1061 -82.7044 No 3,865 Late Cambrian (Maryville Limestone No. 1 I.M. Wheeler (Willard 7.5-min quadrangle) of Conasauga Group). 3 Empire Reeves Steel Madison Township, Richland Co., Ohio 34–139–20448 40.77921 -82.519 Yes1 5,085 Mesoproterozoic (metamorphic and No. D–1 Empire Reeves Steel (Mansfield North 7.5-min quadrangle) (samples end igneous rocks). Division at 4,990 ft) 4 Great Lakes Gas Corporation Wayne Township, Wayne Co., Ohio 34–169–21419 40.8605 -81.9057 Yes1 6,897 Mesoproterozoic (metamorphic and No. 1 Alonzo Drake, Jr. (Wooster 7.5-min quadrangle) igneous rocks). 5 Parker and Chapman Saltcreek Township, Holmes Co., Ohio 34–075–21283 40.65712 -81.7723 Yes1 7,369 Late Cambrian (Maryville Limestone No. 1 Dan E. Troyer (Fredericksburg 7.5-min quadrangle) of Conasauga Group). 6 Stocker & Sitler, Inc. Rush Township, Tuscarawas Co., Ohio 34–157–21030 40.30405 -81.4245 Yes1 8,277 Late Cambrian (Copper Ridge No. 2 (1–2669) Huebner (Gnadenhutton 7.5-min quadrangle) dolomite). 7 Red Hill Development Moorefield Township, Harrison Co., Ohio 34–067–20737 40.195 -81.1972 No 10,625 Mesoproterozoic (metamorphic and No. 1 Thomas Zechman (Piedmont 7.5-min quadrangle) igneous rocks). 8 Sanford E. McCormick Green Township, Harrison Co., Ohio 34–067–20103 40.26188 -80.9664 Yes1 10,181 Late Cambrian (Rose Run sand- No. 1 Roy Birney (Cadiz 7.5-min quadrangle) stone). West Virginia 9 Sanford E. McCormick Liberty District, Marshall Co., W. Va. 47–051–00539 39.76167 -80.53 Yes1 16,512 Late Cambrian (Copper Ridge No. 1 John Burley (Cameron 7.5-min quadrangle) Dolomite). 10 Phillips Petroleum Company Winfield District, Marion Co., W. Va. 47–049–00244 39.43194 -80.0122 Yes1 17,111 Early and Middle Ordovician (Beek- No. A–1 (A–1251) R.R. Finch (Fairmont East 7.5-min quadrangle) mantown Dolomite). 11 Columbian Fuel Corporation Union District, Preston Co., W. Va. 47–077–00119 39.23791 -79.5734 Yes1 7,164–7,437 9,910 Late Ordovician (Reedsville Shale). No. USA Q–1, GW–1466, (Lead Mine 7.5-min quadrangle) (Tuscarora Sandstone) Monongahela National Forest 12 Shell Oil Company Union District, Grant Co., W. Va. 47–023–00002 39.19472 -79.1417 Yes1 13,000 Early and Middle Ordovician (Consolidated Gas Supply (Greenland Gap 7.5-min quadrangle) (Beekmantown Group) thrust over Corporation) Ordovician (Beekmantown Group, No. 1 Greenland Lodge, Inc. St. Paul Group, Black River Lime- stone, and Trenton Limestone). 13 Exxon Corporation Moorefield District, Hardy Co., W. Va. 47–031–00021 39.1375 -78.9903 Yes2 9,791–9,821 16,075 Early and Middle Cambrian No. 1 Charles H. Bean, et al. (Old Fields 7.5-min quadrangle) (Copper Ridge (Waynesboro Formation) thrust Dolomite); over Early and Middle Ordovician 11,047–11,107 (Beekmantown Group). (Elbrook Formation) Sources of lithologic logs: 1Geological Sample Log Company, Pittsburgh, Pa. 2Exxon mud log. Structural Framework 3 1980a; Geological Sample Log Company Log no. others (1987), Boswell (1988a,b), Dennison and others top of the Devonian Berea Sandstone and the Devo- P–2285). (1988), and de Witt and others (1993) for the Devonian nian Onondaga Limestone. Where applicable, strati- The correlation of stratigraphic intervals between rocks; Couchot and others (1980), Majchszak (1984), graphic units on the cross section are tied to the outcrop drill holes and (or) coreholes was based on a variety of Matchen and Vargo (1996), Hohn (1996), Vargo and using the geologic maps of Ohio (Slucher and others, geophysical (wireline) and lithologic logs. The most Matchen (1996), and Dulong and others (2002) for the 2006) and West Virginia (Cardwell and others, 1968) commonly used geophysical logs were the gamma-ray- Mississippian and Pennsylvanian rocks. and, locally, unpublished maps by the West Virginia neutron and gamma-ray-density log suites; the most Only selected unconformities are shown on cross Geological and Economic Survey (Nick Fedorko, West commonly used lithologic logs were those produced section D–D′. Regional unconformities shown on sec- Virginia Geological and Economic Survey, oral com- by the Geological Sample Log Company (table 1). tion D–D′ and in figure 2 include the Middle Ordovi- mun., 2005). Gamma-ray logs used for correlations were digi- cian (Knox) unconformity (Harris and Repetski, 1982; tized as Log ASCII files (LAS), converted to graphic Mussman and others, 1988), the Upper Ordovician- images, and then plotted next to their respective drill Lower Silurian Cherokee unconformity (Dennison Structural Framework holes (Crangle, 2007). The lithology assigned to each and Head, 1975; Diecchio and Brodersen, 1994), the stratigraphic interval was simplified to just a few Middle-Upper Devonian unconformity (de Witt and The western margin of the Valley and Ridge rock types and lithologic modifiers. The topographic others, 1993), and the Lower Pennsylvanian uncon- province (fig. 1) is located at the western limb of the profile for the cross section was created from a Shuttle formity (Arkle and others, 1979; Beuthin, 1994). The Wills Mountain anticline. Beneath the Wills Mountain Radar Topography Mission (SRTM) 90-meter (m)- correlation of these unconformities with North Ameri- anticline is a thick allochthonous panel of Cambrian- grid digital elevation model (DEM) for parts of Ohio, can sequences of Sloss (1988) is shown in figure 2 and Ordovician carbonate rocks (Broad Top sheet of Wilson Pennsylvania, West Virginia, Maryland, and Virginia in Swezey (2002). and Shumaker, 1992) that decoupled from the underlying (http://gisdata.usgs.gov/website/seamless/index.asp). Basement-involved structures along cross section strata and was thrust 12 to 15 mi westward over a par- This topographic profile is approximate and should not D–D′ are modified from structure contour maps by Shu- be used to determine accurate surface elevations. maker (1996) and Baranoski (2002) and from seismic- autochthonous panel of Cambrian-Ordovician carbonate A summary of the stratigraphic units and names based interpretations by Kulander and Ryder (2005). rocks (Plateau sheet of Wilson and Shumaker, 1992). identified along section D–D′ is shown in figure 2 (on High-amplitude, complex, thin-skinned ramp anti- The footwall ramp, which is shown on the easternmost sheet 1). Although most correlations shown on section clines (Etam, Deer Park-Leadmine, Blackwater, Wills part of the cross section beneath drill hole 13, connects D–D′ are based on our own interpretations, many corre- Mountain, and Patterson Creek Mountain) near the the basal zone of detachment (footwall flat) in the Lower lations are adopted or modified from previous publica- Allegheny structural front were constructed on section Cambrian Waynesboro Formation with a higher zone of tions, and stratigraphic nomenclature follows existing D–D′ largely on the basis of interpretations by Wilson detachment (hangingwall flat) in the Upper Ordovician terminology wherever possible. Useful references (1985a,b,c, 1989) and Wilson and Shumaker (1992). Reedsville Shale (thrust fault terminology from McClay, for stratigraphic correlations and (or) nomenclature Low-amplitude anticlines in central West Virginia are 1992). A net structural relief of about 2 mi was created include the following: Colton (1970), Patchen and oth- based on a structure contour map by Cardwell (1982) by the duplicated Cambrian Conasauga Group-Elbrook ers (1985), Milici and de Witt (1988), Swezey (2002), that represents the structure on top of the Devonian Formation in the anticline. Another consequence of and Slucher (2004) for the entire Paleozoic section; Onondaga Limestone-Huntersville Chert. The Chestnut this major structural dislocation is the juxtaposition of Janssens (1973), Diecchio (1985), Riley and Baranoski Ridge anticline that was drilled by drill hole 10 marks steeply dipping lower Paleozoic carbonate and siliciclas- (1991a,b), Ryder (1991, 1992), Wickstrom and others the approximate westernmost limit of thin-skinned tic rocks of the frontal Wills Mountain anticline against (1992), Riley and others (1993), and Harris and others anticlines shown on the cross section. Northwest of the less deformed upper Paleozoic rocks of the Allegheny (2004) for the Cambrian and Ordovician rocks; Clifford Chestnut Ridge anticline, structural dip along the cross Plateau structural province (Kulander and Dean, 1986). (1973), Janssens (1977), Smosna and others (1977), section is largely determined by connecting equivalent This abrupt juxtaposition of structural styles defines the Hettinger (2001), and Ryder (2004) for the Silurian formation tops between drill holes. However, in Ohio Allegheny structural front. rocks; Dennison (1970), Majchszak (1980a,b,c), Schwi- the regional dip is locally based on structure contour Basement-involved and thin-skinned (terminol- etering (1980a,b), Filer (2002, 2003), Boswell and maps by Gray (1982a,b) that represent the structure on ogy from Rodgers, 1949) structures are shown on cross 4 Geologic Cross Section D–D’ From the Findlay Arch, Ohio, to the Valley and Ridge Province, West Virginia section D–D′, and their geometry, style, and timing and others, 1993). Most isotopic ages of these rocks Grenville front (fig. 1; Baranoski and Wickstrom, 1991; are briefly discussed. More detailed treatments of the range between 950 and 1,350 mega-annum (Ma), and Wickstrom and others, 1992; Baranoski, 2002). structural styles and patterns of the central Appalachian many ages cluster around 1,000 to 1,100 Ma (Rankin The Coshocton zone, a 50-to 60-mi-wide zone of basin are presented by Faill (1997a,b, 1998) and Scan- and others, 1993) (fig. 2). Lidiak and others (1966) east-verging penetrative deformation in the Grenville lin and Engelder (2003). The basement structures are reported a K-Ar age of 935 Ma for gneiss and schist in basement, is located approximately between drill holes largely extensional in origin, and several of them may the No. 1 Bruns drill hole (Sandusky County, Ohio), 5 and 9 in the eastern Ohio and westernmost West Vir- have evolved during the Neoproterozoic-earliest Cam- which is located about 25 mi west of drill hole 1 and ginia part of cross section D–D′. On the basis of deep brian rifting of the eastern continental margin of North in the No. 1 Arting drill hole (Huron County, Ohio), seismic reflections on COCORP profiles, this zone is America (Rankin and others, 1989; Thomas, 1991). which is located about 7 mi north of drill hole 2 (fig. 1). interpreted by Culotta and others (1990) as the site of This rifting event was followed by the opening of the As shown on nearby cross section E–E′ (fig. 1), Lidiak an intra-Grenville province suture zone. Younger base- Iapetus Ocean and the construction of a passive margin and others (1966) reported a Rb-Sr age of 860 Ma for ment structures discussed in the following paragraphs along the eastern side of North America (Rankin and biotite granite in drill hole 5 and a K-Ar age of 850 Ma seem to have no relation with structures in the Coshoc- others, 1989; Thomas, 1991). A Middle Cambrian for granodiorite gneiss in drill hole 11. Although these ton zone. event, which was more moderate in scale than the ages reported by Lidiak and others (1966) are younger Typical of many foreland basins, the basement Neoproterozoic-earliest Cambrian rifting event, formed than the 950 Ma upper limit of Grenville basement of the Appalachians is a homoclinal ramp that dips the Rome trough about 200 mi inland from the evolv- rocks suggested by Rankin and others (1993), they are gently from an interior craton to the external margin of ing passive margin (Beardsley and Cable, 1983; Read, grouped in this report with rocks of the Grenville prov- a fold and thrust belt. Along section D–D′, this base- 1989a,b; Shumaker, 1996). In contrast, the major ince. Basement rocks in drill hole 1 of this cross section ment ramp deepens progressively southeastward from thin-skinned structures are contractional in origin are described as medium-grained granite that contains about 3,000 ft below mean sea level (MSL) beneath and probably developed during Late Mississippian- predominantly orthoclase and quartz and accessory the eastern flank of the Findlay arch to about 23,500 Permian continental collision (Alleghanian orogeny) biotite and plagioclase (McCormick, 1961). Moreover, ft below MSL beneath the Allegheny structural front. between eastern North America and Africa (Rodgers, basement rocks in drill holes 12 to 14 in nearby cross This gradual eastward deepening of the basement ramp 1988; Hatcher and others, 1989). Crustal contraction section E–E′ are described, respectively, as granite along section D–D′ is interrupted by the Rome trough that accompanied the collision caused large horizontal gneiss, gneiss and granite, and quartz-oligoclase-biotite (fig. 1), a Middle Cambrian rift system that drops displacements of thick panels of Paleozoic strata along gneiss that contains graphite and sillimanite (King and basement to as much as 26,000 ft below MSL. The thin, incompetent Paleozoic strata. Typical Appalachian others, 1998). Van Schmus and others (1996) reported western limit of the Rome trough is defined here as the thin-skinned structures are bedding-plane detachment a Sm-Nd age of 1,272±32 Ma for gabbro basement in down-to-the-east normal fault located several miles zones, footwall ramps, ramp anticlines, and imbricate drill hole 3 on cross section E–E′ (see Wickstrom and west of drill hole 9 (Shumaker, 1996; Baranoski, 2002), thrust faults (Rodgers, 1963; Gwinn, 1964; Wilson, others, 1985, for a description of the rocks in the drill whereas the eastern limit of the Rome trough is defined 1985a,b,c, 1989; Kulander and Dean, 1986; Wilson and hole) but could not explain the absence of Grenville- as the down-to-the-west normal fault (later reactivated) Shumaker, 1992). In places, the Alleghanian orogeny age (Mesoproterozoic) penetrative deformation and about 5 mi east of drill hole 10 (Shumaker, 1996; reactivated basement faults and locally inverted the associated resetting of the apparent age. The western Kulander and Ryder, 2005). Rome trough (Harris, 1978; Shumaker and Wilson, margin of the Grenville province is marked by the Minor inflection points or hinge zones in the base- 1996; Scanlin and Engelder, 2003; Kulander and Ryder, Grenville front (fig. 1) along which intensely deformed ment ramp probably occur near drill holes 3, 5, and 6 in 2005). Grenville-age metamorphic and igneous rocks (com- north-central Ohio, and a major 30-mi-wide hinge zone monly characterized by west-verging thrust faults, extends between drill hole 8 in eastern Ohio to about Basement Structures Culotta and others, 1990) are juxtaposed against mildly midway between the Ohio-West Virginia border and deformed 1,470-Ma rocks of the eastern granite-rhy- drill hole 9. The north-central Ohio inflection point near Basement rocks along cross section D–D′ con- olite province (fig. 1). The basement-involved Bowl- drill hole 3 coincides approximately with the Waverly sist largely of igneous and metamorphic rocks of the ing Green fault zone, located about 40 mi beyond the arch (fig. 1), a north-trending basement arch identi- subsurface extension of the Grenville province (Rankin western end of the cross section, coincides with the fied by Woodward (1961) from isopach patterns in the Structural Framework 5 Cambrian-Ordovician Knox Dolomite and mapped by probably resulted from contraction during the Late (Shumaker, 1996; Shumaker and Wilson, 1996) and Janssens (1973) and Shearrow (1987). According to Mississippian-Permian Alleghanian orogeny. underlies the Laurel Hill anticline (fig. 1). We sug- Root and Onasch (1999), the Waverly arch is a base- The best example of Alleghanian basin inver- gest that the Laurel Hill anticline was initiated by mild ment uplift that formed during the Taconic orogeny as sion on section D–D′ is shown by the Chestnut Ridge inversion along the eastern margin boundary fault of a result of contrasting anisotropies across lithotectonic anticline where well 10 was drilled (fig. 1). This the Rome trough, during Alleghanian contraction, in boundaries in the Grenville basement rocks. The 30-mi- anticline shows evidence of both thin-skinned and a manner akin to the initiation of the Chestnut Ridge wide hinge zone between drill holes 8 and 9 coincides basement deformation. As shown on the cross sec- anticline on section D–D′. Inversion along the east- approximately with the Ohio-West Virginia hinge zone tion, the Chestnut Ridge anticline clearly involves ern boundary fault zone of the Rome trough formed of Ryder (1991, 1992) that marks the western margin of the Middle Devonian Huntersville Chert (Cardwell, deep-seated structural relief that disrupted westward- the Rome trough (fig. 1). Where section D–D′ crosses 1982), probably as a result of thin-skinned detachment propagating zones of bedding-plane detachment in in the underlying Upper Ordovician Reedsville Shale Ordovician and Silurian strata that were approximately the Rome trough, the trough is about 45 to 50 mi wide (Kulander and Ryder, 2005) and Upper Silurian Salina synchronous with the inversion. Disrupted detachment and has a structural relief on basement that ranges Group (Gwinn, 1964; Wilson, 1985b). Furthermore, zones beneath the Chestnut Ridge and Laurel Hill anti- from several hundred feet at its western margin across the anticline is interpreted here to be deeply rooted and clines were transformed onto complex imbricate faults down-to-the-east normal (extensional) faults to an involve lower Paleozoic strata and Mesoproterozoic (both northwest and southeast verging) and triangle estimated 4,000 to 5,000 ft at its eastern margin across basement rocks, judging from the structural geometry zones (Scanlin and Engelder, 2003). Even in areas down-to-the-west normal (extensional) faults. Most shown by a seismic line (Kulander and Ryder, 2005) without structural inversion, the basement-involved basement faults of the Rome trough in the cross section that crosses the Chestnut Ridge anticline about 5 to 10 fault zones of the Rome trough commonly imposed a have been recognized in previous studies (Shumaker, mi south of drill hole 10 (fig. 1). Because the deeply northeast-trending positive structural grain on Meso- 1996; Baranoski, 2002; Kulander and Ryder, 2005). A rooted part of this anticline occurs below any zones of proterozoic basement rocks and overlying Cambrian basement block, called the central West Virginia arch known bedding-plane detachment, it is interpreted here strata along which imbricate faults were concentrated (Kulander and Dean, 1986), flanks the eastern margin to be caused by mild basin inversion associated with (Scanlin and Engelder, 2003). of the Rome trough and dips gently eastward beneath the reversal in motion of the eastern boundary fault of Another possible example of Alleghanian basin the Allegheny structural front and the western part of the Rome trough during the Alleghanian orogeny. inversion on section D–D′ is shown by the Hundred the Valley and Ridge province. The eastern part of the Approximately 8 to 9 mi northeast of cross section anticline located about 7 mi east of drill hole 9. This arch may be broken into several blocks by down-to-the- D–D′, the Chestnut Ridge anticline diverges from the anticline is interpreted to be deeply rooted on the basis east normal (extensional) faults that involve basement eastern margin boundary fault of the Rome trough and of a seismic line (Kulander and Ryder, 2005) that beneath and east of the Etam and Wills Mountain anti- continues into southwestern Pennsylvania (fig. 1). On crosses the colinear Arches Fork anticline approxi- clines (Jacobeen and Kanes, 1975; Shumaker, 1996). the basis of seismic data, Scanlin and Engelder (2003) mately 30 mi south of the cross section. The reactivated Most normal (extensional) faults associated with showed that the Chestnut Ridge anticline in southwest- basement fault shown on the seismic section (Kulander the Rome trough rift system were reactivated several ern Pennsylvania is underlain by a downdropped west- and Ryder, 2005) dips northwestward beneath the times during the Paleozoic to produce either renewed ern basement block in the Rome trough graben system, Arches Fork anticline, whereas the reactivated base- subsidence or small-scale basin inversion (Shumaker but evidence for inversion is lacking. Furthermore, ment fault shown on section D–D′ dips southeastward and Wilson, 1996). For example, small-scale basin Scanlin and Engelder (2003) showed that thin-skinned beneath the Hundred anticline. inversion has been documented along segments of structures are more characteristic of the Chestnut Ridge Yet another basement structure on section D–D′ the Rome trough in northern West Virginia and south- anticline in this area than basement-involved structures, may be the northwest-trending Parkersburg-Lorain western Pennsylvania where basement-involved which contrasts with the Chestnut Ridge anticline on syncline, which is present approximately 10 mi west normal (extensional) faults were reactivated as reverse section D–D′. From where it diverges from the Chest- of drill hole 4. This structure is a broad south-plunging (contractional) faults to create mildly inverted gra- nut Ridge anticline (8–9 mi northeast of section D–D′), syncline on a structure contour map on the top of the bens (Scanlin and Engelder, 2003; Kulander and the eastern margin boundary fault of the Rome trough Berea Sandstone (Gray, 1982a), but the syncline does Ryder, 2005). Most of the small-scale inversion trends northeastward into southwestern Pennsylvania not appear on a structure contour map on the top of the 6 Geologic Cross Section D–D’ From the Findlay Arch, Ohio, to the Valley and Ridge Province, West Virginia Onondaga (Columbus) Limestone (Gray, 1982b). From In drill hole 12, the master tectonic ramp-thrust block by Wilson (1989), but Wilson and Shumaker its location on section D–D′, the Parkersburg-Lorain fault of the Wills Mountain anticline is located 8,500 (1992) later abandoned the term. syncline extends southward to the Ohio-West Virginia ft below MSL where allochthonous Lower Ordovician Within and east of the Wills Mountain anticline, border, and from there the Parkersburg syncline extends Beekmantown Group rocks rest in thrust contact on several thrust faults branch off the master thrust fault a short distance into West Virginia (fig. 1). Along most an overturned syncline that involves Lower to Upper (hangingwall flat) of the Broad Top sheet of Wilson of this trend, the syncline is flanked by the Cambridge Ordovician carbonate rocks and shale (W.J. Perry, Jr., and Shumaker (1992) and divide the sheet into three arch (Cambridge cross strike structural discontinuity of USGS, unpub. data, 1980). The drill hole bottomed in subsheets (or horses) (see figure 3). The easternmost Baranoski, 2002), which is interpreted as a basement the upright limb of the overturned syncline, which is subsheet (3) forms the Broad Top anticline, the west- structure (Root, 1996; Baranoski, 2002). Gray (1982a, considered in this report to be a horse block that was ern part of which is shown at the eastern end of cross b), Riley and others (1993), and Baranoski (2002) derived from the eastern margin of the Plateau sheet and section D–D′. The thrust fault that forms the Broad have suggested that the northern end of the Cambridge is now lodged between the main allochthonous sheet Top anticline is located in drill hole 13 about 14,000 arch-cross strike structural discontinuity terminates in (Broad Top sheet) and the underlying subhorizontal ft below MSL where several repeated sections of the Coshocton or Holmes Counties (fig. 1). However, judg- parautochthonous sheet (Plateau sheet) (see figure 3 on Waynesboro Formation rest in thrust contact on the ing from the apparent genetic relation between the arch sheet 2). Additional structural complications in the Wills Beekmantown Group. This thrust fault that forms the and the abrupt westward limit of Silurian halite beds Mountain anticline, shown on section D–D′ and based Broad Top anticline joins the upper zone of detach- that trends northwestward across central Ohio (Clif- on repeated strata in drill hole 12, are imbricate faults ment in the Reedsville Shale (roof thrust) about 1 to ford, 1973; Farmerie and Coogan, 1995; Root, 1996), (at approximate depths of 3,200 and 6,100 ft below 2 mi west of drill hole 13, and also very likely offsets both the arch and the Parkersburg-Lorain syncline may ground level) that branch from the master thrust and the roof thrust. Subsheet 2 of the Broad Top sheet the synclinal horse block. These imbricate faults cut the forms the Patterson Creek Mountain anticline, which is extend at least as far north as cross section D–D′ or core of the anticline and probably the roof thrust in the located 2 to 3 mi west of drill hole 13. Imbricate thrusts even farther. Ordovician Reedsville Shale at the crest of the anticline. that splay off the roof thrust in the Reedsville Shale cut Also, at the crest of the Wills Mountain anticline, the Upper Ordovician to Upper Devonian strata in the Pat- Thin-Skinned Structures roof thrust bends sharply westward to conform with the terson Creek Mountain anticline. The western subsheet steep western frontal limb of the anticline to merge with (1) of the Broad Top sheet forms the majority of the Thin-skinned structures on cross section D–D′ the top of the hangingwall flat in the master thrust (in the Wills Mountain anticline. Also, subsheet 1 of the Broad include the Broad Top, Patterson Creek Mountain, Reedsville Shale) beneath the Allegheny structural front Top sheet overrides the previously described synclinal Wills Mountain, Blackwater, Deer Park-Leadmine, (Wilson and Shumaker, 1992). Moreover, the master horse block that is lodged between the Broad Top and Etam, and Chestnut Ridge anticlines at the eastern end thrust or ramp of the Wills Mountain anticline and the Plateau sheets. of the cross section. These anticlines are high-ampli- underlying horse block were folded by a deeper thrust- From its juncture with the master thrust of the tude, commonly west-verging structures that formed ramp that branched off the basal zone of detachment and Broad Top sheet at the eastern end of section D–D′, the during the Late Mississippian-Permian Alleghanian joined the hangingwall flat in the Reedsville Shale about basal detachment in the Lower to Middle Cambrian orogeny (Gwinn, 1964; Kulander and Dean, 1986; Wil- 5 mi west of drill hole 12. This deeper thrust fault-ramp Waynesboro Formation continues farther westward for son and Shumaker, 1992). The Wills Mountain (upper is one of several secondary thrusts that subdivide the an estimated 50 to 55 mi beneath the Plateau sheet to part), Patterson Creek Mountain, and Broad Top anti- parautochthonous Plateau sheet of Wilson and Shumaker near the eastern edge of the Rome trough. West-verging clines (including the Clearville syncline that overlies (1992) into five subsheets (see figure 3). According to thrust faults branch upward from this basal detachment the western margin of the Broad Top anticline in the McClay (1992), thrust-fault-bounded structures such as in the Waynesboro Formation, subdivide the Plateau subsurface) belong to the Broad Top sheet of Wilson subsheets 2 to 5 also may be classified as horses. The sheet into the previously mentioned five subsheets, and and Shumaker (1992), whereas the Etam, Deer Park- thrust fault-ramp that folded the master thrust beneath join a higher detachment in the Reedsville Shale that Leadmine, Blackwater, and Wills Mountain (lower the Wills Mountain anticline is the easternmost of the extends westward from the Wills Mountain anticline. part) anticlines belong to the Plateau sheet of Wilson lower thrust subsheets (5) (see figure 3). This eastern- Except for the western subsheet (1), each of these thrust and Shumaker (1992). most subsheet was originally named the Wills Mountain faults-subsheets has carried a panel of Cambrian and